In order to comply with requirements to improve energy efficiency, counter measures are proposed to recover heat of gas exhausted to the atmosphere, i.e., exhaust heat, and reuse it in various industries. Particularly, in a field of an automobile having an internal combustion engine, in order to improve a total heat efficiency, it is getting popular that an exhaust heat recovery apparatus for recovering heat of the exhaust gas from the internal combustion engine is installed in an exhaust pipe, and cooling medium or coolant heated by heat exchanging with the exhaust heat is used for accelerating the warming up of the engine, or improving the heating performance. For example, Patent document 1 discloses such an exhaust heat recovery apparatus “that is provided with a heat exchanger for heat exchanging with the exhaust gas, a bypass passage for the exhaust gas to bypass the heat exchanger, and a valve member for opening or closing the bypass passage, wherein a temperature-operated actuator which comes into contact with medium immediately after it was discharged from the heat exchanger, so that the temperature-operated actuator is elongated when the temperature of the medium is equal to or higher than a predetermined value, to open the valve member” (described in paragraph (0008) of Patent document 1).
Furthermore, with respect to the exhaust heat recovery apparatus as described above, such a structure is disclosed in Patent document 1 “that an inlet cone, an outlet cone, a bypass vale and a heat exchanger are fitted into each other and fixed air-tightly by welding or the like, and that the bypass pipe and an upstream end portion of the heat exchanger are fitted into the inlet cone, whereas the bypass pipe and a downstream end portion of the heat exchanger are fitted into the outlet cone” (described in paragraph (0013) of Patent document 1, with reference numerals as indicated therein being omitted). With respect to the heat exchanger, it is further described “that in a casing, 9 heat-transfer pipes having flat cross section are fluid-tightly fixed to partition plates, into which their opposite end portions are penetrated”, and “that between two partition plates, a water jacket for the medium flowing therein is formed by the inner surface of the casing and the outer surfaces of the heat-transfer pipes” (described in paragraph (0014), with reference numerals as indicated therein being omitted).
Also, Patent document 2 discloses such a heat exchanger “that a plurality of heat-transfer tubes for flowing exhaust gas therein are stacked one over another, and the heat-transfer tubes are accommodated in a core case, which is provided with an inlet port for introducing a medium and an outlet port for discharging the medium warmed in the heat-transfer tubes, so that the medium is flowed from the inlet port toward the outlet port, and the exhaust gas is flowed into the heat-transfer tubes, whereby the medium flowed through the outer periphery of the heat-transfer tubes is warmed by the heat of the exhaust gas. At least 3 heat-transfer tubes are stacked one over another, and, with the heat-transfer tubes equal to or more than 3 being stacked one over another, the passages, which are formed between the upper surfaces of the heat-transfer tubes and the core case, between the heat-transfer tubes adjacent to each other, and between the lower surfaces of the heat-transfer tubes and the core case, are formed into 4 and more layers as viewed in cross section, so that passages between layers for the medium being transferred to another layer are formed between the side surfaces of the heat-transfer tubes and the core case.” And, such a configuration as to “close any passage between layers by a passage closing means” is proposed (described in paragraph (0009) of Patent document 2).
Furthermore, Patent document 2 discloses such a configuration “that an exhaust heat recovery apparatus comprises an introducing member, to which exhaust gas generated from an internal combustion engine is introduced, a heat exchanger, which is connected with the introducing member through an upper passage, and a tip end of which is supported by a gas introducing member, a gas discharging member, which is connected to a rear end of the heat exchanger, and in which the exhaust gas passed through the heat exchanger is flowed, a lower passage, which is disposed below the heat exchanger, and in which the exhaust gas that is not flowed into the upper passage, is flowed, a thermo-actuator, which is supported by an actuator support portion at a medium discharging portion, to be actuated by a medium temperature, and a valve mechanism, which is disposed at a tip end of the actuator to adjust the amount of exhaust gas flowed in the upper passage” (described in paragraph (0032) of Patent document 2, with reference numerals as indicated therein being omitted).